OBJECTIVE: To define contemporary age- and sex-related mortality risks and patterns of medical practice in acute myocardial infarction (AMI). DESIGN: Retrospective comparison of demographic and clinical variables, including the use of proven effective AMI medical therapy, among AMI patients cohorts from 1987 to 1992. PATIENTS/SETTING: Of a total of 2,070 AMI patients, 629 were women and 1,441, men; 951 patients were managed in university hospitals, 641 in a regional hospital, and 478 in community hospitals. INTERVENTIONS: No direct study interventions; results of practice patterns and risk analyses of the earlier (1987-90) AMI cohorts, however, were published concurrently with the actual practices of the more recent (1991-92) cohorts and may have had some indirect effect on the recent practice patterns. RESULTS: Univariate analysis showed that mortality was higher (p < 0.0001) and use of thrombolysis, beta blockers, and acetylsalicylic acid was lower (p < 0.0001) in patients 70 years of age and older, compared with younger patients, and in women, compared with men. Multivariate analysis of the entire patient sample revealed age of 75 years or older (154 percent) and age 70 to 74 years (141 percent) to be associated with the highest relative risk of death in hospital. The increased relative risk associated with previous AMI was 45 percent. Acetylsalicylic acid use was associated with the greatest decrease in relative risk of death (-69 percent), followed by beta blockers (-36 percent) and thrombolysis (-31 percent). These patterns of relative risk were the same for men and women. CONCLUSIONS: Among contemporary AMI patients, advanced age and female sex are associated with relative under-utilization of proven effective medical therapy and increased risk of dying in the hospital. Although the contribution of age to AMI risk appears greater than that of gender, survival in any high risk group would likely be improved by increased use of proven medical therapy.